A. Field of the Invention
This invention relates to the control and sequencing of printers and particularly to controlling and sequencing the sheet feed and drum transport and the array transport.
B. Prior Art
Printers, such as those used in copiers, have in the past controlled and sequenced in various ways the mechanisms for feeding the sheet, transporting the drum, and transporting the array which applies the ink. In view of the mechanical nature of these mechanisms, certain operating parameters are critical during a printing cycle, e.g., acceleration and deceleration. These mechanisms function satisfactorily while these critical parameters are within certain tolerances. There have been two basic choices in setting up such tolerances for printer operation. First, if the printer is set to function within a narrow tolerance band, the printer then has good operating performance while the critical parameters remain within that band. This usually requires frequent and costly service calls by service personnel to maintain satisfactory operation by adjusting those narrow tolerances. Secondly, printers set up with a wide tolerance band at the factory result in machines having large performance variations among machines. For example, where a critical parameter involves the speed of the machine, with a wide band of tolerances a fast machine will sometimes give poorer overall performance than a slower machine though both machines are within the tolerance band. Thus, in a particular example of an ink jet printer in a copier system, a fast acting servo actually causes the system to perform more poorly than a slower acting servo because a fast servo brings the print drum down to load speed quickly. The print drum, however, must remain at the lower load speed until a paper load point on the drum has been reached since the printer can accept paper only at certain load points. Thus, there has been no gain, but rather a loss, in efficiency when the drum reaches a slow load speed at an early time. For maximum system efficiency, the fast servo should have remained longer at the faster print speed in order that a load point on the drum be brought up sooner.
Accordingly, an object of the present invention is to adapt the operation of a printer to its critical parameters that actually exist and are being used rather than within some arbitrary tolerance band.
Another object is substantially to eliminate critical adjustment of the printer mechanism by determining the existing running values of the critical parameters and using these existing running values as a profile for use during the printing cycle.